"beginner" is a pretty broad term.
what i'd recommend, is setting up 20 Interceptor wings, and 10 Helicopter wings, and max upgrade them. if you upgrade them to 450, then later on, when you have trouble, you can double them, with the extra being 330Q, and end up with 40 I-wings at 390. Its unlikely that another newb will have enough Offensive air wings that have a high enough Quality to match, that is if you can get federation air support, which you can set up with your own countries.
Set up about a dozen large and small supply units, with LT, and LTA. If you manage to fill your garrisons, you'll need more of these.
as far as garrisons. for your capital, cities, and bases, you'll need nuke D. 10 NDB, with 50 missiles each. as far other weapons, thats gonna depend on your available funds, and manpower.
further with garrisons, its unlikely that you will fill each garrison. focus your heavier garrisons in your capital, cities, and bases. for starters on those, try 100 each of AAMB, DMB, and MIB. with maybe 100 Armored Vehicles, or light tanks. And default ammo.
for your factories and forts, if you can, do the same. and for your towns and countries, try setting those with 50 ish Light tanks, to prevent the bad guy from taking over empty territory.
try to spread out your targets, especially the ones with tanks. to get maximum blockage of enemy troops. you can do this via the map controls. this is something that must be done before war is declared.
keep in mind. for any serious threat, you'll need a federation. as the garrisons i've mentions are rather light.